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Pituitary Microadenomas Clinical Presentation

  • Author: Bernard Corenblum, MD, FRCPC; Chief Editor: George T Griffing, MD  more...
Updated: Jul 25, 2016


Types of pituitary microadenomas

Nonsecreting incidentalomas usually have no associated symptoms. They are ordinarily found in people who have radiologic studies for other reasons (eg, headaches). Unlike macroadenomas, incidentalomas are too small to cause pressure-related symptoms such as headache, diplopia, or visual-field loss.

Prolactinomas may be asymptomatic if prolactin levels are only slightly elevated. In women, hyperprolactinemia may cause galactorrhea, oligorrhea/amenorrhea, decreased libido, or infertility. In men, hypogonadism, erectile dysfunction, and decreased libido may ensue. Galactorrhea is rare in men.

Corticotropin-secreting adenomas cause Cushing disease.

Growth hormone–secreting adenomas cause acromegaly.

Thyroid-stimulating hormone (TSH)–secreting adenomas are a very rare cause of hyperthyroidism, and the patient has a nonsuppressed serum TSH level.

Gonadotropin-secreting adenomas have been reported. The frequency is rare. Women may present with amenorrhea and a mismatch between estrogen and gonadotropin levels (eg, elevated gonadotropin levels despite normal or elevated levels estrogen levels without suppression of gonadotropins).[11] They may be misdiagnosed as having ovarian failure.



Any physical abnormalities are caused by excessive hormone secretion (eg, galactorrhea due to hyperprolactinemia, acromegaly due to excessive growth hormone, corticotropin-mediated Cushing disease). Most microadenomas found incidentally on CT scan or MRI are clinically inactive.

Patients with prolactin-secreting adenomas may present with galactorrhea. Other causes of galactorrhea need to be excluded, such as hypothyroidism and chest wall lesions.

Growth hormone–secreting adenomas cause acromegaly with coarsening of facial features and increased width of the hands and feet. Progressive bony proliferation of the mandible both lengthens and thickens it, resulting in separation of the lower teeth and an underbite. Skin thickness is increased compared with age- and sex-matched controls (>2 mm in reproductive-aged women, >3 mm in men).

Corticotropin-secreting adenomas cause Cushing disease characterized by weight gain, primarily in the facial, nuchal, truncal, and girdle areas (ie, centripetal or "buffalo" obesity). Protein breakdown leads to thin, friable skin that bruises easily; this breakdown may form wide striae that are often purple. The protein breakdown often causes muscle weakness (proximal muscles more than distal muscles), wasting, and osteopenia with fragility fractures. Women often develop hirsutism. In children, growth is arrested.



As with adenomas elsewhere, the likely cause of pituitary microadenomas is a local mutation leading to autonomous growth and/or secretion. A variety of tumor suppressor genes and oncogenes have been described in sporadic pituitary tumorigenesis.[12]

Contributor Information and Disclosures

Bernard Corenblum, MD, FRCPC Professor of Medicine, Director, Endocrine-Metabolic Testing and Treatment Unit, Ovulation Induction Program, Department of Internal Medicine, Division of Endocrinology, University of Calgary Faculty of Medicine, Canada

Disclosure: Nothing to disclose.

Specialty Editor Board

Francisco Talavera, PharmD, PhD Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Received salary from Medscape for employment. for: Medscape.

Chief Editor

George T Griffing, MD Professor Emeritus of Medicine, St Louis University School of Medicine

George T Griffing, MD is a member of the following medical societies: American Association for the Advancement of Science, International Society for Clinical Densitometry, Southern Society for Clinical Investigation, American College of Medical Practice Executives, American Association for Physician Leadership, American College of Physicians, American Diabetes Association, American Federation for Medical Research, American Heart Association, Central Society for Clinical and Translational Research, Endocrine Society

Disclosure: Nothing to disclose.


David M Klachko, MD, MEd Professor Emeritus, Department of Internal Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Missouri-Columbia School of Medicine

David M Klachko, MD, MEd is a member of the following medical societies: Alpha Omega Alpha, American College of Physicians-American Society of Internal Medicine, American Diabetes Association, American Federation for Medical Research, Missouri State Medical Association, Sigma Xi, and The Endocrine Society

Disclosure: Nothing to disclose.

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MRI showing a nonenhancing area in the pituitary consistent with a microadenoma in a patient with hyperprolactinemia.
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